//    CANAPE Network Testing Tool
//    Copyright (C) 2014 Context Information Security
//
//    This program is free software: you can redistribute it and/or modify
//    it under the terms of the GNU General Public License as published by
//    the Free Software Foundation, either version 3 of the License, or
//    (at your option) any later version.
//
//    This program is distributed in the hope that it will be useful,
//    but WITHOUT ANY WARRANTY; without even the implied warranty of
//    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//    GNU General Public License for more details.
//
//    You should have received a copy of the GNU General Public License
//    along with this program.  If not, see <http://www.gnu.org/licenses/>.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using CANAPE.DataFrames;

namespace CANAPE.DataAdapters
{
    /// <summary>
    /// A data adapter which reads frames from an IEnumerable
    /// </summary>
    public abstract class EnumerableDataAdapter : BaseDataAdapter
    {
        private IEnumerator<DataFrame> _enumerator;

        /// <summary>
        /// Overridable method to get frames
        /// </summary>
        /// <returns>Return an IEnumerable for the frames</returns>
        protected abstract IEnumerable<DataFrame> GetFrames();

        /// <summary>
        /// Read the next frame
        /// </summary>
        /// <returns>The frame, null on EOS</returns>
        public sealed override DataFrame Read()
        {            
            if (_enumerator == null)
            {
                _enumerator = GetFrames().GetEnumerator();
            }
            
            if(_enumerator.MoveNext())
            {
                return _enumerator.Current;
            }

            return null;
        }
    }
}
